1. Field of the Invention
The present invention generally relates to cryogenic coolers and more specifically, to cryogenic cooler systems capable of continuous and uninterrupted cooling within the system.
2. Description of Prior Art
Cryogenic cooling in certain applications require continuous and uninterrupted cooling within the cooler system. Previous applications include: space experiments, surveillance, and strategic defense sensors. One type of space application of cryogenic cooling requires continuous cooling to cryogenic temperatures for 5-10 years. Space applications have long life requirements since repair is not realistic. This life requirement has caused a major problem since the typical operating time of the cryogenic cooling is on the order of 50,000-90,000 hours. In addition, a high coefficient of performance (COP) is required because input power requirements aboard a spacecraft must be minimized. A cryogenic cooler, which has shown the highest COP at cryogenic temperatures, is the Stirling cycle and its derivatives. However, the life requirement has led to new variations of this cooler which are very expensive to produce and large in size.
In the prior art, the Oxford-type, diaphragm compressor, and magnetic bearing, have all been tried as ways to eliminate surfaces from contacting each other. The Oxford devices use two dimensional springs to create a non-contact clearance seal for a linear drive system. Similarly, magnetic bearings also use magnetic fields to eliminated rubbing surfaces. These approaches have been successful but at a price of 100 times the cost of the prior art Stirling cooler. In addition to the extra weight, these cooler approaches are not applicable to systems where large quantities of coolers are needed because of cost and size. Many systems require hand fitted tolerances and have still not demonstrated the required reliability when environmental conditions are factored in.
While the prior art has reported using cryogenic coolers, none have established a basis for a specific apparatus that is dedicated to the task of resolving the particular problem at hand. What is needed in this instance is a cryogenic cooler system capable of continuous and uninterrupted cooling within the system with minimized moving parts.